Dingy soils and stains are a common problem on articles of clothing. The composition of "dingy" stains can vary. Some fabrics may have limited areas of "dingy" stain (armpits, elbows) while others appear "dingy" in their entirety. Typically, laundry detergent compositions are not effective in removing this dingy soils and stains from fabric.
It has now surprisingly been found that certain metallocyanine compounds are effective against "dingy" soils or stains. For the purposes of the present invention the term "dingy" soils or stains refers to dirt, oils, grime, soil, or other staining material that accumulate on fabric and are not effectively removed by the action of detersive surfactants.
It is known that certain water-soluble phthalocyanine and naphthalocyanine compounds, optionally complexed with certain metals, have a singlet oxygen generation action and can therefore be used as photo-bleaching agents or anti-microbial active agents.
"Singlet oxygen" is an oxidative species capable of reacting with stains to chemically bleach them to a colorless and usually water-soluble state, a process called photochemical bleaching. Common photochemical bleaches include zinc and aluminum phthalocyanines.
The prior art teaches phthalocyanine and naphthalocyanine compounds having the general structure ##STR1##
where Me is a transition or non-transition metal, (Sens.) is a phthalocyanine or naphthalocyanine ring which, when combined with a suitable Me unit, is capable of undergoing photosensitization of oxygen molecules, R represents one or more substituent groups which are bonded to the photosensitization ring units (Sens.) to enhance the solubility or photochemical properties of the molecule, and Y represents one or more substituents associated with the metal atom, for example, anions to provide neutrality. The selection of particular substituents R for substitution into the molecule has been the focus of many years of research.
A major limitation of phthalocyanine and naphthalocyanine as compounds for fabric photobleaching is that these molecules are highly colored as the Q-band, the main absorption band, is in the range of visible light. As a consequence of their high color, photobleaches can stain or hue fabrics.
A second limitation arises from the fact that many phthalocyanine and naphthalocyanine compounds including their transition or non-transition metal complexes are not inherently water soluble. This is especially true in the case of naphthalocyanines. It has therefore been the task of photobleach formulators to identify R substituents that increase the molecule's water solubility without adversely affecting its photochemical effectiveness.
A further task for formulators of photobleaches has been the need to modify the properties of the phthalocyanines and naphthalocyanines to improve their photobleaching capacity (photophysics), which includes increasing the quantum efficiency. Selection of suitable R units to accomplish this task must not in turn adversely affect the water solubility. While balancing water solubility and enhanced photophysics, the formulator must insure that the structural modifications do no shift the .lambda..sub.max of the Q-band to a wavelength that increase the color of the photobleach.
The present invention allows the formulator to modify solubility, photoefficiency, Q-band wavelength maxima and the electronic requirements of the central metal atom independently. This ability to delineate and selectively modify the key structural elements contributing to the properties of the photobleach provides the formulator with greater flexibility in obtaining the desirable properties described above.
It has now been surprisingly discovered that by manipulation of one or more axial substituents, hereinafter axial R units which are nonionic and axial T units which are anionic, photobleaching compositions can be produced which are effective in removing the "dingy" stain from soiled fabric. The R axial moiety is selected for its ability to allow the photobleaching compound to partition into the layer of "dingy" soiling material where it then acts to photobleach the material.
It is an object of the present invention to provide photobleaching compounds which can effectively remove or bleach dingy soils on fabric or hard surfaces.
It is a further object of the present invention to provide photobleaching compositions for non-aqueous and low aqueous application, that is, photobleaching compositions for use with cleaning solutions wherein water constitutes less than half of the carrier liquid.
It is a further object of the present invention to provide photobleaching compositions and cleaning compositions comprising substantive materials for non-porous hard surfaces, inter alia, Formica.RTM., ceramic tile, glass, or for porous hard surfaces such as concrete or wood.
An object of the present invention is to provide a method for bleaching fabric with laundry compositions comprising metallocyanine photosensitizing compounds of the present invention.
An object of the present invention is to provide for low hue metallocyanine photosensitizing compounds having a Q-band maximum absorption wavelength of at least 660 nanometers.